Conversion of hydrocarbon oils



Aug. 24, 1937. K. sw wo b 2,090,878

CONVERSION OF HYDROCARBON OILS Filed Oct. 8, 1934 FRACTIONATOR COIDEN SER l5,

FURNACE 2,

CONDEN SER 55 INVENTOR KENNETH SWgTWOOD BY (1% 7 ATTOR EY Patented Aug. 24, 1937 UNlTE STTES PATENT OFFIQE 2,090,878 CGNVERSION or nYnnooAeBoN onis Application October 8,

Claims.

This invention particularly refers to an improved process for the selective conversion of relatively low-boiling and high-boiling hydrocarbon oils.

In one specific embodiment, the invention comprises subjecting an oil of relatively low-boiling characteristics to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil, commingling hydrocarbon oil charging stock for the process, preferably comprising an oil of relatively wide boiling range, with the stream of highly heated products from said heating coil and introducing the commingled materials into a reduced pressure vaporizing chamber wherein the charging stock conversion prodnets are subjected to further vaporization together with the charging stock and wherein vaporous and nonwaporous materials are separated, subjecting the vapors from said vaporizing chamber to fractionation, whereby their components boilin above the range of the desired light distillate product are condensed as reflux condensate and separated into selected relatively low-boiling and high-boiling fractions, subjecting fractionated vapors of the desired end-boiling point to condensation, collecting and separating the resulting distillate and gas, returning selected low-boiling fractions of said reflux condensate to the heating coil for further conversion, subjecting selected high-boiling fractions of said reflux condensate to independently controlled conversion conditions of elevated temperature and superatmospheric pressure in a separate heating coil and communicating reaction chamber, withdrawing liquid remaining unvaporized in said vaporizing chamber therefrom and introducing the same into said reaction chamber to commingle therein and be subjected to conversion with the heated products from the last mentioned heating coil, withdrawing both vaporous and liquid conversion products from the reaction chamber and introducing the same into a separate reduced pressure vaporizing chamber, withdrawing residual liquid remaining unvaporized in said separate vaporizing chamber therefrom, subjecting vaporous products from said separate vaporizing chamber to fractionation in a separate fractionating zone, whereby their insufficiently converted components are condensed as reflux condensate, subjecting fractionated vapors of the desired endboiling point from said separate fractionator to condensation, collecting and separating the resulting distillate and gas and returning reflux condensate from said separate fractionator to the first mentioned fractionator for separation 1934, Serial No. 147,260

therein into selected relatively low-boiling and high-boiling fractions for further treatment togeth r with the corresponding previously mentioned low-boiling and high-boiling fractions from this zone.

The features and advantages of the present invention may be better understood with reference to the accompanying diagrammatic drawing, illustrating one specific form of apparatus embodying the features of the present invention and in which the process of the present invention may be accomplished. Various modifications of the specific embodiment above described which are within the scope of the present invention are also included in the following description of the drawing. Such modifications are, however, not to be considered equivalent but may be chosen to suit the particular characteristics and requirements of the oil undergoing treatment to produce the desired final results.

Referring to the drawing, hydrocarbon oil of relatively low-boiling characteristics is supplied from within the system, as will be later more fully described, to heating coil 5 wherein it is subjected, by means of heat supplied from a furnace 2 of any suitable form, to the desired conversion conditions of elevated temperature and superatmospheric pressure and the heated products are discharged from the heating coil through line 3 and valve 4 into vaporizing chamber 5. Preferably the stream of heated products from the heating coil is commingled in line 3 with hydrocarbon oil charging stock for the process, which is supplied through line 6 and valve 1 to pump 8, by means of which it is fed, in the case here illustrated, through line 9 and valve l0 into line 3. In this manner the charging stock is heated by direct contact with the highly heated products from the heating coil, serving to cool the latter suificiently to prevent their excessive further conversion, and the charging stock is subjected to vaporization in chamber 5, which is preferably maintained at a substantially reduced pressure relative to that employed at the outlet from the heating coil in order to assist cooling of the conversion products and permit further vaporization of the liquid con version products as well as the charging stock supplied to this zone.

Separation of liquids and vapors is accomplished in chamber 5 which, in the particular case here illustrated, comprises the lower portion of fractionating column. I I, and the vapors pass from chamber 5, through communicating line l2 into the upper portion of the fractionating column, wherein their components boiling above the range of the desired light distillate product are condensed as reflux condensate.

Fractionated vapors of the desired end boiling point are withdrawn, together with uncondensable gas, from the upper portion of column ll through line l3 and valve l4 and are subjected to condensation and cooling in condenser 15. The resulting distillate and gas pass through line l6 and valve H to collection and separation in receiver l8. Uncondensable gas may be released from the receiver through line l9 and valve 20.

Distillate may be withdrawn from receiver l8 through line El and valve 22. When desired, a regulated portion of the distillate collected from receiver 3 may be recirculated by well known means, not illustrated in the drawing, to the upper portion, of column H to: serve as a cooling and refluxing medium to assist fractionation of the vapors and to maintain, the desired vapor outlet temperature from the fractionator.

In the case here illustrated the reflux condensate formed in column H is separated into se- 1ected relatively low-boiling and high-boiling frac tions. The low-boiling fractions may be withdrawn from one or a plurality of suitable intermediate points in the fractionator, being directed, in the case here illustrated, through line 23 and valve 24 to pump 25, by means of which they are returned through line 25 and valve 21 to further conversion in heating coil I. The high-boiling fractions of the reflux condensate formed in column H are withdrawn from the lower portion of the fractionator through line 23 and valve 28 to pump 36 by means of which they are supplied through line 3! and valve 32 to heating coil 33 for further conversion.

Heating coil 33 is located within a suitable furnace 34, of any desired form, which supplies the required heat to the oil passing through the heating coil to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure, and the heated oil is directed from heating coil 33 through line 35 and valve 35 into reaction chamber 31.

Chamber 3'! is also preferably maintained at a substantial superatmospheric pressure and, although not indicated in the drawing, is preferably insulated to prevent the excessive loss of heat therefrom by radiation so that conversion of the materials supplied to this zone, and particularly their vaporous components, may continue therein.

Liquids remaining unvaporized in chamber 5, comprising liquid conversion products from heating coil 1 and any high-boiling components of the'charging stock supplied to chamber 5, as previously described, which remaining unvaporized in this zone, may be withdrawn from the lower portion thereof through line 38 and valve 39 to i pump 45 by means of which they are fed through line and may be directed, all or in part, through valve 42, in this line, into reaction chamber 31, to comrningle therein with the heated products from heating coil 33 and be subjected therewith to the conversion conditions maintained in the reaction chamber.

In the case here illustrated, both vaporous and liquid conversion products are withdrawn in commingled state from the lower portion of chamber 3'! through line 43 and valve 44 and are introduced into vaporizing chamber 45, which is preferably maintained at a substantially reduced pressure relative to that employed in the reaction chamber, by means of which further vaporization of the liquids supplied to this zone is accomplished.

It is also within the scope of the present invention, when desired, instead of supplying liquids from chamber 5 to chamber 31 to direct all or a regulated portion thereof into vaporizing chamber 45. This may be accomplished, as here illustrated, by diverting the oil from line ii through line 46 and valve 41 into line 4-3, to commingle therein with the vaporous and liquid conversion products passing from the reaction chamber to the vaporizing chamber, or this material may be supplied direct to the vaporizing chamber by well known means, not illustrated in the drawing. In case this method of operation is employed little or no appreciable further conversion of the total components of the liquid from chamber 5 will be accomplished in chamber 45 but this material will be subjected to further vaporization in chamber 45, its non-vaporous high-boiling components connningling in this zone with the residual liquid conversion products from chamber 31 while its vaporized components pass, together with the vaporous conversion products from chamber 45, to further treatment, as will be later more fully described.

Residual liquid remaining unvaporized in chamber 45 may be withdrawn therefrom through line 48 and valve 49 to cooling and storage or to any desired further treatment. Vapors are directed from chamber 45 through line 55 and valve 5| to fractionation in iractionator 52, wherein their insufficiently converted components are condensed as reflux condensate which is subjected to further conversion within the same system, as will be later more fully described.

Fractionated vapors of the desired end-boiling point are withdrawn, together with uncondensable gas, from the upper portion of fractiator 52 through line 53 and valve 54 and are subjected to condensation and cooling in condenser The,

resulting distillate and gas pass through line 56 and valve 5'? to collection and separation in receiver 58. Uncondensable gas may be released from the receiver through line 59 and valve Distillate may be withdrawn fromv receiver 58.

through line 6! and valve 82 to storage or to any desired further treatment. A regulated portion of the distillate collected in receiver 58 may, when desired, be recirculated to the upper portion of fractionator 52, by well. known means, not illustrated, for the purpose of cooling and assisting fractionation of the vapors in this zone and maintaining the desired vapor outlet temperature from the fractionator.

The reflux condensate formed in fractionator I 52 may be withdrawn from the lower portion thereof through line 63 and valve 64 to pump 65 by means of which it is fed through line and may be directed through valve 51 in this line into fractionator ll, wherein it comes into direct contact with the vapors undergoing fractionation in this zone and is thereby vaporized and subjected to fractionation therewith for separation, as previously indicated, into selected relatively lowboiling and high-boiling fractions, the low-boildesired, to direct the reflux condensate from fractionator 52 to further conversion in heating coil. 33. This may be accomplished by diverting the oil from line 66 through 68 and valve 69 into line- 3| and thence to heating coil 33. On the other hand, fractionator 52 may be. dispensed with, when desired, and the vaporous products from chamber 55 supplied to fractionator H or, when desired, the reflux condensate formed in fractionator 52 may be separated therein into relatively low-boiling and high-boiling fractions for return to heating coils l and 33 respectively, although these provisions are, for the sake of simplicity, not shown in the drawing.

The preferred range of operating conditions which may be employed in the operation of the. process of the present invention, when utilizing an apparatus of the general character illustrated and above described, may be approximately as follows: The first mentioned heating coil, to which the relatively low-boiling oils are supplied, may utilize a conversion temperature, measured at the outlet therefrom, of the order of 900 to 1050 F., preferably with a substantial superatmospheric pressure at this point in the system of from 200 to 800 pounds, or more, per square inch although, when desired, lower pressures down to substantially atmospheric may be employed. The vaporizing chamber succeeding this heating coil is preferably operated at substantially atmospheric or a relatively low superatmospheric pressure ranging up to 100 pounds, or thereabouts, per square inch. This pressure may be substantially equalized or somewhat reduced in the succeeding fractionating, condensing and collecting portions of this stage of the system. The other heating coil of the process, to which the relatively high-boiling oils are supplied, may uti- 'lize an outlet conversion temperature ranging,

.35 for example, from 850 to 950 F., or thereabouts, preferably with a superatmospheric pressure, measured at the outlet from the heating coil, of from 100 to 500 pounds, or more, per square inch. The reaction chamber may utilize a pressure sub- 40 stantially the same or somewhat lower than that employed at the outlet from the communicating heating coil and the succeeding vaporizing chamber is preferably operated at a substantially reduced pressure ranging, for example, from 100 pounds, or thereabouts, per square inch, downto substantially atmospheric pressLhe. The fractionating, condensing and collecting portions of the last mentioned stage of the system may employ pressures substantially the same or somewhat lower than the pressure employed in the preceding vaporizing chamber.

As a specific example of the operation of the process of the present invention as it may be accomplished in an apparatus such as illustrated and above described, utilizing as charging stock a reduced crude of about 22 A. P. I. gravity, the light oil heating coil employs an outlet conversion temperature of approximately 970 F., with a pressure measured at the outlet from the heat- 60 ing coil of approximately 600 pounds per square inch which is reduced in the vaporizing chamber to approximately 100 pounds per square inch.

The charging stock is commingled with the stream of heated oil passing from the light oil 65 heating coil to the vaporizing chamber whereby the heated products are cooled to below a temperature at which any appreciable further conversion thereof will occur and whereby the charging stock is heated sufficiently to eiTect its sub- 70 stantial vaporization. Residual liquid withdrawn from the vaporizing chamber succeeding the light oil heating coil is supplied to the reaction chamber. An overhead vaporous product from the fractionator of the first cracking stage 75 having an end-boiling point of approximately 385 F. is subjected to. condensation and the resulting distillate recovered. Low-boiling reflux condensate fromthis zone having a boiling range of approximately 3'70 to 600 F., is returned to the light oil heating coil for further conversion. The high-boiling fractions of the reflux condensate from this zone are. subjected to further conversion in a separate heating coil employing an outlet temperature of approximately 950 F. at a superatmospheric pressure of about 350 pounds per square inch and the heated products: are introduced into the reaction. chamber of the system which is maintained at substantially the] same pressure. The vaporizing chamber succeeding the reaction chamber employs a superatmospheric'pressure of approximately pounds per square inch which is substantially equalized in the succeeding fractionating, condensing and collecting portions of the system. Reflux condensate from the fractionator of the last mentioned cracking stage is returned to the fractionator of the first cracking stage. This. operation will produce, per barrel of charging stock, approximately 52 percent of motor fuel having an antiknock value equivalent to an octane number of aproximately 70 and about 38 percent of good quality fuel oil, the remainder being chargeable, principally, touncondensable gas and loss.

I claim as. my invention:

1. In a process for the selective conversion of relatively low-boiling and high-boiling hydrocarbon oils wherein a relatively low-boiling oil is subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil, the stream of heated products from said heating coil commingled with hydrocarbon oil charging stock for the process, of relatively Wide boiling range, and the cornmingled materials introduced into a reduced pressure vaporizing chamber wherein separation of vaporous and liquid productsis accomplished, the vaporous products subjected to fractionation, whereby their components boiling above the desired light distillate product are condensed as reflux conden} sate and separated into selected relatively lowboiling and high-boiling fractions, fractionated vapors of the desired end-boiling point subjected to condensation and the resulting distillate collected, the improvement which comprises returning said low-boiling fractions of the reflux condensate to the heating coil for further conversion, subjecting said high-boiling fractions of the reflux condensate to independently controlled conversion conditions of elevated temperature and superatmospheric pressure in a separate heating coil and communicating reaction chamber, withdrawing both vaporous and liquid conversion products from the reaction chamber, subjecting the latter to further vaporization in a separate reduced pressure vaporizing chamber wherein vaporous and liquid conversion products separate, supplying liquids remaining unvaporized in the first-mentioned vaporizing chamber to said reaction chamber, withdrawing residual liquid from said separate vaporizing chamber, subjecting the vaporous conversion products from the last mentioned conversion stage, including the vapors evolved by said further vaporization of the liquid products, to fractionation, whereby their insufliciently converted components are condensed as reflux condensate, and separated into relatively low-boiling and high-boiling fractions which are returned, respectively to the first mentionedand last mentioned heating coils, subjecting fractionated vapors of the desired end-boiling point to condensation and collecting the resulting distillate.

' 2. In a process for the selective conversion of relatively low-boiling and high-boiling hydrocarbon oils wherein a relatively low-boiling oil is subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil, the stream of heated products from said heating coil commingled with hydrocarbon oil charging stock for the process, of relatively wide boiling range, and the commingled materials introduced into a reduced pressure vaporizing chamber wherein separation of vaporous and liquid products is accomplished, the vaporous products subjected to fractionation, whereby their components boiling above the desired light distillate product are condensed as reflux condensate and separated into selected relatively lowboiling and high-boiling fractions, fractionated vapors of the desired end-boiling point subjected to condensation and the resulting distillate collected, the improvement which comprises supplying said low-boiling fractions of the reflux condensate to the heating coil for further conversion, subjecting said high-boiling fractions of the reflux condensate to independently controlled conversion conditions of elevated temperature and superatmospherio pressure in a separate heating coil and communicating reaction chamber, withdrawing both vaporous and liquid conversion products from the reaction chamber, subjecting the latter to further vaporization in a separate reduced pressure vaporizing chamber wherein vaporous and liquid conversion products separate, supplying liquids remaining unvaporized in the first-mentioned vaporizing chamber to said separate. vaporizing chamber, withdrawing residual liquid from said vaporizing chamber, subjecting the vaporous conversion products from the last mentioned conversion stage, including the vapors evolved by said further vaporization of the liquid products, to fractionation in a separate fractionating zone, whereby their insufiiciently converted components are condensed as reflux condensate, subjecting fractionated vapors of the desired endboiling point to condensation, collecting the resulting distillate and returning the last mentioned reflux condensate to said separate heating coil for further conversion.

3. A process of the character defined in claim 2 wherein said liquids remaining unvaporized in the first mentioned vaporizing chamber are sup plied to said separate vaporizing chamber by heing first introduced to the reaction chamber to commingle therein with the heated products from said separate heating coil and be subjected therewith to conversion under the conditions maintained in the reaction chamber.

4. A hydrocarbon oil conversion process which comprises heating a relatively light oil to crack ing temperature under pressure in a heating coil and then commingling the same with charging oil from the process, separating the commingled oils into vapors and unvaporized oil in a sepa-' rating zone, fractionating the vapors to separate relatively heavy and light reflux condensates therefrom, returning the light reflux condensate to said coil, subjecting the heavy reflux conden sate to independently controlled cracking conditions of temperature and pressure in a second heating coil and a reaction zone, removing unvaporized oil from the separating zone and passing the same through the reaction zone in admixture with the heated heavy reflux condensate from said second coil, discharging reaction products from the reaction zone into a reduced pressure vaporizing zone and therein separating the same into vapors and residue, fractionating the lastnamed vapors and returning at least a portion of the resultant reflux condensate to said second coil, and finally condensing the fractionated vapors.

5. A hydrocarbon oil conversion process which comprises heating a relatively light oil to cracking temperature under pressure in a heating coil and then commingling the same with charging oil for the process, separating the commingled oils into vapors and unvaporized oil in a separating zone, fractionating the vapors to separate relatively heavy and light reflux condensate therefrom, returning the light reflux condensate to said coil, subjecting the heavy reflux conden sate to independently controlled cracking conditions of temperature and pressure in a second heating coil and a reaction zone, removing unvaporized oil from the separating zone and commingling the same with reaction products from KENNETH SWARTWOOD. 

